Unique effects of energy versus estrogen deficiency on multiple components of bone strength in exercising women

Many female athletes are energy and/or estrogen deficient, but the independent effects on bone health have not been isolated. Energy deficiency was detrimental at the tibia while estrogen deficiency was detrimental at the radius. Nutrition must be considered alongside menstrual recovery when addressing compromised bone health in female athletes.

The purpose of this study was to describe volumetric bone mineral density (vBMD), bone geometry, and estimated bone strength in exercising women (n = 60) grouped according to energy status (energy replete (EnR: n = 30) vs. energy deficient (EnD: n = 30)) and estrogen status (estrogen replete (E₂R: n = 33) vs. estrogen deficient (E₂D: n = 27)), resulting in four distinct groups: EnR + E₂R (n = 17), EnR + E₂D (n = 13), EnD + E₂R (n = 16), EnD + E₂D (n = 14).

Energy status was determined using the ratio of measured to predicted resting energy expenditure (mREE/pREE). Estrogen status was based on self-reported menstrual status confirmed by daily evaluation of urinary estrone-1-glucoronide (E1G), pregnanediol glucuronide (PdG), and luteinizing hormone (LH). Eumenorrheic women were considered E₂R, amenorrheic women were E₂D, and oligomenorrheic women were categorized based on history of menses in the past year. Bone was assessed using peripheral quantitative computed tomography (pQCT).

EnD women exhibited lower total vBMD, trabecular vBMD, cortical area, and BSI at the distal tibia and lower total vBMD, smaller cortical area and cortical thickness, and larger endosteal circumference at the proximal tibia compared to EnR women (p < 0.042). E₂D women had lower total and cortical vBMD, larger total and trabecular area, and lower BSI at the distal radius and lower cortical vBMD at the proximal radius compared to E₂R women (p < 0.023). Energy and estrogen interacted to affect total and trabecular area at the distal tibia (p < 0.021).

Efforts to correct energy deficiency, which in turn may promote reproductive health, are warranted in order to address the unique contributions of energy status versus estrogen status to bone health.